 |
| Myloplus sauron Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, Myloplus aylan Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, Myloplus schomburgkii (Jardine, 1841) in Machado, Pereira, Ota, Collins, Ândrade, Garcia-Ayala, Jégu, Farias et Hrbek, 2024 |
Abstract
Presently, Myloplus schomburgkii is the most easily recognized species among the serrasalmids by having a vertical black bar in the middle of the body. However, through a broad taxonomic review, including DNA barcoding and morphological analyses, we were able to identify and describe two new species that also share a dark vertical bar on the flank. In addition, we redescribe M. schomburgkii, designating a neotype and restricting the type-locality to rio Negro in Barcelos, Amazonas State, Brazil. The three lineages of black-barred pacus present high molecular divergences (7.9–11%) and can be distinguished by differences in the shape of the vertical bar, shape of females’ anal fin, number of total vertebrae, number of total branched dorsal-fin rays, among other characters. Although the existence of these two new species has been hidden due to many morphological similarities, mainly the presence of the black bar, the three lineages do not compose a monophyletic group, with one of the new species being recovered as sister to Ossubtus xinguense. This result reinforces the necessity of the redefinition of the Myleini genera.
Keywords: Amazon basin; COI; DNA barcoding; Myleini; Neotype
 |
Myloplus sauron, color pattern in life. Young specimen from Xingu River basin, specimen not preserved. Myloplus schomburgkii, color pattern immediately after capture. A. INPA 60149, neotype, 203.9 mm SL, male, with second lobe well developed and remarkable breeding coloration. B. INPA 52507, 197.1 mm SL, female. Both from Amazonas, Barcelos municipality, rio Negro. Myloplus aylan, coloration immediately after capture. Mature female, lago Uauaçu, Purus River basin. Photographed by Lucia Rapp Py-Daniel. |
Myloplus aylan Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, new species
Diagnosis. Myloplus aylan can be distinguished from all congeners, except M. schomburgkii and M. sauron n. sp. (described below), by the presence of a vertical black bar on the flank commonly extending from the dorsal-fin base to the pelvic-fin distal end (vs. absence of any conspicuous mark on the flank in the rest of the congeners). The new species can be diagnosed from M. schomburgkii and M. sauron by the following characters: parietal bone with dorsal surface markedly concave in lateral view (vs. straight to slightly concave), 82–95 (mode 84) total perforated scales on lateral line [vs. 68–87 (mode 79) in ...
Etymology. The specific name honors the late Aylan Moraes Andrade, Carine Moraes and Marcelo Andrade’s son, born on December 23, 2022, who passed away prematurely on July 6, 2023. Marcelo is one of the authors of this manuscript and this is a tribute to record all the love and dedication of his parents who will never forget him. A noun in apposition.
Myloplus sauron Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, new species
Etymology. The specific name sauron alludes to the Eye of Sauron, from J. R. R. Tolkien’s “The Lord of the Rings”. The elliptical body of Myloplus sauron, marked with a vertical, black bar tapering toward both ends, resembles the famous vertical-pupilled eye from the novel. A noun in apposition.
 |
| Sympatric occurrence of Myloplus schomburgkii (left) and M. aylan (right) in rio Água Boa do Univini, tributary of rio Branco. Both specimens are mature males, the specimens has not being preserved. |
Myloplus schomburgkii (Jardine, 1841)
Etymology. Myloplus schomburgkii was described in honor of Robert H. Schomburgk, who, during an expedition to English Guyana, collected individuals of the species, took notes, and illustrated (Fig. 14) the specimen used by Jardine (1841) to describe the new species. A genitive noun.
Valéria N. Machado, Victória D. Pereira, Rafaela P. Ota, Rupert A. Collins, Marcelo Ândrade, James R. Garcia-Ayala, Michel Jégu, Izeni P. Farias and Tomas Hrbek. 2024. Integrative Taxonomy of the Black-barred Disk Pacus (Characiformes: Serrasalmidae), including the Redescription of Myloplus schomburgkii and the Description of Two New Species. Neotrop. ichthyol. 22 (2); DOI: 10.1590/1982-0224-2023-0095
